And now we’ve been given a glimpse into her postpartum health and fitness routine. Aussie exercise entrepreneur Kelly Rennie has revealed that the Duchess of Cambridge used her popular postnatal program after giving birth to Prince George in 2012.

“To get the letter back from Kate showed us the program could work for any mum," she told Caters News.

Kelly createdBusy Mums Fitnessafter she lost 20 kilograms and overcame crippling depression by overhauling her health and fitness.The Gold Coast native said she was shocked to receive praise from Kate herself and has now released a new version of herguide.

“It meant so much at the time. That routine was a postnatal program, whereas this one is a sustainable fitness routine for the months that follow.

“If Kate can do it with the first two, she can do it with the third. She just needs to keep the same principles she applied after her first two kids as she obviously has managed to look after herself well!”